1. Field of the Invention
This invention relates to fluid pumps, such as might be used in water or oil wells, and more specifically to an air lift pump having a plurality of lift stages and employing a minimum number of moving parts.
2. Description of the Prior Art
Many different systems have been devised for lifting liquid from wells to the earth's surface. These systems have employed various types of pumps, including gas lift pumps, electrically operated centrifugal down hole pumps, sucker rod actuated pumps and so forth. In oil wells, the most common means of pumping the oil to the surface is by the use of a string of sucker rods vertically reciprocated within the well. At the bottom of the string of sucker rods is a pump supported in a string of tubing. The pumping unit at the earth's surface utilizes power, supplied by an engine or motor, to raise and lower the sucker rods and thereby the pump plunger to lift fluid in the tubing from the bottom to the top. In this type of pumping system, which works satisfactorily, a substantial amount of energy imparted to the mechanism is employed in the actuation of the mechanism and only a relatively small percent is utilized in the effort involved to lift the fluid itself.
The present invention is directed towards an improvement in a type of air lift pump in which air pressure is used as the lifting force. The pumping system is arranged such that the fluid is lifted in sequence steps, as opposed to a system for lifting the entire fluid column from the bottom of the well to the top. In the present system, fluid is lifted from one lifting cylinder to the next upper adjacent lifting cylinder. The total head against which the fluid must be lifted is dependent only on the spacing between adjacent lifting cylinders. For instance, the lifting cylinders may be spaced approximately 150 feet apart. The pumping system of this invention is arranged such that the amount of air pressure which is required to lift the fluid from the bottom of the well to the top, regardless of the total depth of the well, is only that which is required to lift the fluid 150 feet. In this way, the amount of energy lost in the pumping process is greatly reduced; the amount of energy utilized in lifting the fluid column is significantly increased.
Prior art systems operating along the same general principles have employed cylinders with flow barrels operating therein, the cylinders being connected directly with their barrels via valving means. Once valves were shut, insidious pressures, such as head pressure, adhesion and the like, thwarted successful operation of the system by preventing reliable sequencing of operation.
Therefore, it is a feature of this invention to provide an improved air lift pump, sequencing between alternate pair of cylinders, each cylinder having a main body and an internal barrel therein, wherein the valving means therebetween includes a positive force for operating the valving means at each cycling.
It is another feature of the present invention to provide an improved air lift pump, sequencing between alternate pairs of cylinders, each cylinder having a main body and an internal barrel therein, wherein the valving means therebetween includes an intermediate chamber for separating the operation of the valving means with respect to the main body and the barrel and for permitting the fluid from the inlet to be applied directly to the valving means, thereby forcing the float off its seat to allow the produced fluid to enter.
It is still another feature of the present invention to provide an improved air lift pump, sequencing between alternate pairs of cylinders, such that operation is not dependent on emptying of one of said pairs of cylinders before sequencing may occur.
It is yet another feature of the present invention to provide an improved air lift pump, wherein well pressures are always less than or equal to the internal pressure of the cylinder production tubing and air lines; thereby preventing collapsing of these components of the system because of the weight of the fluid column.
It is still another feature of the present invention to provide an improved air lift pump system including improved float valves that resist fluid head collapse pressures in excess of those pressures encountered for wells several hundreds of feet deep in which such system is designed for operation.